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However, in practice, this cannot be achieved, as real signals are always time-limited. So, to mimic the infinite behavior, prefixing the end of the symbol to the beginning makes the linear convolution of the channel appear as though it were circular convolution, and thus, preserve this property in the part of the symbol after the cyclic prefix.
In wireless communication, the term numerology refers to "waveform parametrization, e.g., cyclic prefix, subcarrier spacing." [1] The waveform selection is subject to a set of real-world restrictions, so a practical mobile communication system (with signal propagation conditions that tend to vary significantly from one location to another), utilizes a set of different waveforms, or "multiple ...
For example, a low-complexity scheme referred to as WCP-OFDM (Weighted Cyclic Prefix Orthogonal Frequency-Division Multiplexing) consists of using short filters at the transmitter output in order to perform a potentially non-rectangular pulse shaping and a near perfect reconstruction using a single-tap per subcarrier equalization. [17]
After removing the cyclic prefix at the receiver, a DFT is applied to arrive in the frequency domain, where a simple single-carrier frequency-domain-equalization (SC-FDE) scheme can be employed, followed by the IDFT operation. DFT: Discrete Fourier Transform; IDFT: Inverse Discrete Fourier Transform; CP: Cyclic Prefix; PS: Pulse Shaping
But in long-range Wi-Fi, special technologies are used to get the most out of a Wi-Fi connection. The 802.11-2007 standard adds 10 MHz and 5 MHz OFDM modes to the 802.11a standard, and extend the time of cyclic prefix protection from 0.8 μs to 3.2 μs, quadrupling the multipath distortion protection. Some commonly available 802.11a/g chipsets ...
Two different lengths of the cyclic prefix are available to support different channel spreads due to the cell size and propagation environment. These are a normal cyclic prefix of 4.7 μs, and an extended cyclic prefix of 16.6 μs. LTE Resource Block in time and frequency domains: 12 subcarriers, 0.5 ms timeslot (normal cyclic prefix).
Longer guard periods allow more distant echoes to be tolerated but reduce channel efficiency. For example, in DVB-T, guard intervals are available as 1/32, 1/16, 1/8 or 1/4 of a symbol period. The shortest interval (1/32) provides the lowest protection and the highest data rate; the longest interval (1/4) provides the highest protection but the ...
By using directional antennas and sacrificing some traffic capacity, cell coverage could extend to over 10 kilometres (6.2 mi). One example is the corDECT standard. The first data application for DECT was Net 3 wireless LAN system by Olivetti, launched in 1993 and discontinued